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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Flow boiling of R-134a in a minichannel plate evaporator with augmented surface

Get access (open in a dialog) DOI: 10.1615/IHTC12.5420
6 pages

Abstract

This paper considers flow boiling of R-134a in a minichannel formed by two parallel aluminum plates whose surfaces are augmented by means of round beads. The heat transfer coefficients and pressure drops were evaluated for mass fluxes ranging from 40 to 190 kg/m2·s, and inlet-exit quality bands of 0.25 to 0.50, 0.50 to 0.75 and 0.75 to 0.90. The paper presents in detail the methodology for the evaluation of the heat transfer coefficient. The minichannel evaporator design was evaluated by comparing its performance with a similar plate with a different number of round beads. These results were also compared with available correlations for a better understanding of the heat transfer mechanism in the minichannel. Over the range of parameters tested, an enhancement of two to six-fold in the heat transfer coefficient was obtained compared to smooth tubes with the same nominal area. From the comparison and study of correlations, a simple correlation was proposed which agrees with the experimental data within an uncertainty rate of 20 %.